Charles Ellicott Commentary Numbers 30:6

"And if she be [married] to a husband, while her vows are upon her, or the rash utterance of her lips, wherewith she hath bound her soul," — Numbers 30:6 (ASV)

And if she had at all an husband ... — Better, And if she should be married to a husband while her vows are upon her, or the rash utterance of her lips with which she has bound her soul. The case here considered appears to be that of a woman who married while under a vow. On the other hand, the case of a woman who takes a vow after marriage is discussed later in Numbers 30:10-13. The cognate verb of the word mibta, rash utterance, occurs in Leviticus 5:4, and seems to mean something which is uttered without reflection.